This invention relates to medical, dental, and surgical handpieces, and in particular to a high-speed ball bearing for use in such handpieces.
Medical, dental, and surgical handpieces containing rotary tools supported on high-speed bearings are typically powered by an air turbine or electric motor. In either case, there are some common challenges to long bearing life. During operation, the bearings in such handpieces may be exposed to contamination in the form of both solid and liquid biological matter, as well as in the form of synthetic debris. The handpiece must be cleaned and sterilized between each patient. Typical cleaning and sterilization procedures require flushing of the head of the handpiece with solvents followed by high pressure steam sterilization in an autoclave system. Handpieces can reach temperatures ˜134° C. in autoclaving processes. Both procedures are detrimental to the life of the bearings in that they degrade the properties of many lubricants and retainer materials, as well as remove the lubricant remaining in the bearings. In addition, the cleaning process requires that the head of the handpiece be disassembled so that any foreign matter can be removed from the handpiece head. This is time consuming and can be complicated. For this reason, cleaning of foreign matter (as opposed to sterilization) of medical, dental, and surgical handpieces may not be performed as often as is necessary.
In order to replenish the lubricant within the bearings, the user must inject oil into the drive system of the handpiece, operate the handpiece to expel excess oil and clean any oil residue from the exterior of the handpiece. In addition to the time and expense required to relubricate the handpiece, there is the unwanted added risk that excess lubrication can contaminate the working environment. Unwanted lubricant can be expelled within the handpiece body cavity during patient treatment and can contaminate the surface of the tooth or bone being treated, risking infection or resulting in poor adhesion of a amalgam or “filling” material, such as employed in dental procedures.
For medical, surgical, or dental handpieces having a rotary tool powered by an air driven turbine, air is discharged from exhaust vents located near the top and bottom of the of the handpiece head during use. This exhaust air may pass through the bearings on the way out of the head and accelerate the expulsion of lubricant from the handpiece. While the handpiece is slowing to a stop, the air flow physics of the handpiece are reversed. As the handpiece shuts down, the low pressure caused by the rotating turbine draws debris, into the head of the handpiece and the bearings within.
Accordingly, there is a need for an improved high-speed bearing suitable for application medical, surgical, or dental handpeices to provide support for rotary tools, and which is adapted for easy cleaning, exclusion of external contaminates, and which is configured to facilitate the retention of lubricants within the bearing assembly.